Sacred petroglyphs around Bishop, California, have been defaced and stolen, according to federal authorities.

About 3,500 years ago, ancient hunters and gatherers around present day Bishop etched deer, rattlesnakes, bighorn sheep, hunters and other symbols into the half-mile-long volcanic escarpment in the Eastern Sierra. The petroglyphs survived flash floods, earthquakes and winds, but they couldn’t stand up to a team of quick, outfitted thieves.

"The individuals who did this were not surgeons, they were smashing and grabbing," U.S. Bureau of Land Management archaeologist Greg Haverstock said last week. "This was the worst act of vandalism ever seen" on the 750,000 acres of BLM-managed public land in Bishop.

Four petroglyphs were stolen, others were defaced with deep saw cuts or hammer strikes and one was found broken near a visitor parking lot.

To steal and deface the petroglyphs was no easy feat and required ladders, electric generators and power saws. The thieves gouged holes in the rock and pulled out two foot by two foot slabs of stone up to 15 feet off the ground.

The theft was discovered by visitors who reported it to the BLM on Oct. 31. Bernadette Lovato, the BLM field office manager, had to report the news to the Paiute-Shoshone tribal leaders in Bishop. She told the Los Angeles Times it was “the toughest phone call I ever had to make.”

The desecration of the region known as Volcanic Tableland was a violation of the tribe’s spiritual and cultural beliefs. The area is sacred to the Native Americans whose ancestors etched the stone.

“We will do everything in our power to bring those pieces back,” Lovato said.

The desecration brought together reservation officials and U.S. Authorities to ask how future vandalism can be prevented.

"How do we manage fragile resources that have survived as much as 10,000 years but can be destroyed in an instant?" asked archaeologist David Whitley in an interview with the Los Angeles Times. In 2000, Whitley wrote the nomination that secured the site a spot on the National Register of Historic Places.

The easiest answer would be to police sites listed under the Archaeological Resources Protection Act, but cash-strapped federal lands agencies don’t have the resources to do so, authorities said. Nevertheless, volunteers have stepped up to help survey the area, as well as the other dozens of sites managed by the BLM office in Bishop.

The petroglyphs are only worth $500-$1,500 on the illicit market, but they are priceless to Native Americans who see the carvings as a representation of the souls of their ancestors.

The site is also important for archeologists, who see it as a representation of the culture and spirituality of the ancient tribes in the Eastern Sierra.

As he approached the site earlier this month, officer Raymond Andrews quietly chanted a traditional prayer in observation of sacred law.

"We still use this sacred place as a kind of church to educate tribal members and children about our historical and spiritual connections,” he told the Los Angeles Times. “So, our tribal elders are appalled by what happened here."

Federal authorities and Native American leaders plan to install small signs by each defaced petroglyph that will point out the terrible damage.

Defacing or removing petroglyphs is a felony and the BLM is offering a $1,000 reward for information that could lead to the arrest and conviction of the people responsible for the damage. First-time offenders can face fines up to $20,000 and one year in prison. Second-time offenders may be required to pay up to $100,000 and imprisonment of up to five years.